Dental handpiece and collet wrench therefor



M. STAUNT 3,325,899 DENTAL HANDPIECE AND COLLET WRENCH THEREFOR June 20,1967 2 Sheets-Sheet 1 Filed Sept. 25, 1964 44 45 INVENTOR:

MARTIN STAUNT M BY L age/ 112050 ATT YS M. STAUNT 3,325,899

DENTAL HANDPIECE AND COLLET WRENCH THEREFOR June 20, 1967 2 Sheets-Sheet2 Filed Sept. 25, 1964 INVENTOR. MARTIN STAUNT BY Q ATT'YS v OE UnitedStates Patent 3,325,899 DENTAL HANDPIECE AND COLLET WRENCH THEREFGRMartin Staunt, Des Plaines, llll., assignor, by mesne assignments, toAmerican Hospital Supply Corporation,

Evanston, Ill., a corporation of Illinois Filed Sept. 25, 1964, Ser. No.399,247 17 Claims. (Cl. 3Z-27) ABSTRACT OF THE DISCLOSURE Thecombination of a collet-equipped dental handpiece and a Wrench foradjusting the collet, the wrench having a non-circular shaft insertableinto a central end-wall opening in the handpiece for rotating thecollet, and having one or more parallel locking pins which fit intosockets in the rotor through an opening in the same end wall of thehandpiece for holding the rotor stationary during such adjustment.

Collets have long been known in the art, including the dental handpieceart, for releasably holding tools or burs in place. In the case ofconventional beltdriven handpieces the provision of collets which may bereadily adjusted has posed no diflicult problem; such a collet isexpanded or contracted in its tubular rotor simply by screwing itaxially one way or the other while the end of the rotor (normally theend provided with a belt-engaging pulley) is gripped between the fingersand is thereby prevented from rotating. In a turbine-driven handpiece,however, a special problem arises because the rotor is fully encased andcannot be locked against rotation in the usual manner.

While efforts have been made to develop a satisfactory means for lockingthe rotors of turbine-driven handpieces during collet adjustment suchefforts have been generally unsatisfactory. For example, in one proposedconstruction the rotor housing is provided with a side opening throughwhich a tool may be inserted to engage the turbine blades and lock therotor against movement. Such an opening is undesirable because itconstitutes an access port for moisture and particulate matter whichmight enter the rotor chamber and interfere with turbine operation.Furthermore, such an opening provides an outlet for turbine-driving airwhich not only reduces turbine efiiciency but which also directs alateral stream of air to dry the membranes of the mouth and causeconsiderable patient discomfort. There is also the serious possibilitythat even with careful manipulation of the rotor-locking tool theprecisely-formed and delicate blades of the turbine may be damaged ordeformed when such a tool is braced against them during colletadjustment.

In a modified construction, the access opening has been eliminated andthe end of the rotor adjacent the bur is provided with an extension ofnon-circular or hexagonal cross section. A wrench it fitted upon theextension to hold the rotor stationary as the collet is rotatablyadjusted therein. While such a design eliminates some of the problemsinherent in the side-apertured construction described above, it presentsnew problems and disadvantages of at least equal magnitude. Thehexagonal extension, if made large enough for secure attachment of arotorlocking wrench, may cause serious injury to a patient should thehexagonal surfaces contact oral membranes or teeth during high speeddrilling operations. If, on the other hand, the extension is reduced insize to minimize the dangers to patients, the surfaces of the extensionwill be too small to provide secure attachment for a wrench withoutrapid wear or deformation.

3,325,899 Patented June 20, 1967 Summary of invention Accordingly, it isa principal object of the present invention to overcome theaforementioned defects and disadvantages of prior constructions.Specifically, it is an object to provide a collet-equipped air-drivendental handpiece in which the rotor may be easily and firmly locked inplace during collet adjustment without contacting the delicate turbineblades and without providing means which might constitute a potentialsource of injury to a patient.

Another object of the invention is to provide a turbine handpiece inwhich the rotor is adapted to be locked against rotation during colletadjustment and in which such adaptation does not appreciably alter theflow of exhaust air or otherwise interfere with turbine operation. Afurther object is to provide a handpiece in which adjustment of thecollet and locking of the rotor during such adjustment are carried outby operations performed only at one end of the turbine housing. In thisregard, it is a specific object to provide a handpiece construction inwhich such operations are performed only at the housings upper end; thatis, the end opposite from the bur. Another object is to provide ahandpiece and Wrench combination which cooperate in the locking of arotor against rotation while at the same time coupling a collet with thewrench for longitudinal adjustment within the rotor. A further object isto provide a compact wrench which may be easily and quickly coupled tothe upper end of a handpiece for locking a turbine rotor in place andfor adjusting the bur-supporting collet of that handpiece.

Still another object is to provide a collet and rotor construction for adental handpiece which insure proper centering of a bur and whichthereby eliminate or greatly reduce operation vibration and the wear andother disadvantages which would normally be associated with suchvibration. An additional object is to provide a rotor and bur tubeconstruction which not only direct expansion and contraction of a colletbut which also contribute in directing the discharge of cooling airtowards a bur.

Drawings FIGURE 1 is a side elevational view of a dental handpieceembodying the present invention;

FIGURE 2 is an exploded and partially cutaway perspective view of thehead asembly of the handpiece and also illustrating a collet wrench foradjusting the collet of that handpiece;

FIGURE 3 is an exploded perspective view illustrating the majorcomponents within the turbine cartridge illustrated in FIGURE 2; 7

FIGURE 4 is an enlarged longitudinal sectional view of a head assemblyshowing the collet wrench operatively associated therewith;

FIGURE 5 is an exploded perspective view showing the components of thecollet wrench.

Description In the embodiment of the invention illustrated in thedrawings, the numeral 10 generally designates a contraangleturbine-driven dental handpiece having an elongated handle portion A anda head housing B. Other than in the respects pointed out below, such ahandpiece is similar in construction and operation to the handpiecedisclosed in Staunt Patent 3,084,439, issued Apr. 9, 1963. Sinceturbine-driven contra-angle dental handpieces are now well known in theart, a detailed description of the components which constituteenvironmental elements for the structure of the present invention isbelieved unnecessary herein.

Within the the housing B is a cartridge assembly C which comprises acartridge casing 11, stator 12, spaced ball bearing assemblies 13 and14, and a rotor comprising bur tube 15, turbine 16, and tubular colletor chuck 17. The cartridge assembly also includes a bur tube nut 18. Anexternally-threaded cap D constitutes a part of the complete housing Band is threadedly connected to the remainder of the housing to securethe cartridge assembly in place.

The rotor, comprising turbine 16, bur tube 15, chuck 17, and nut 18, issupported for rotation within the housing by bearing assemblies 13 and14. As shown most clearly in FIGURE 4, cap D is provided with aninternal shoulder 19 which bears against the outer race of upper bearingassembly 13. The inner races of the upper and lower bearing assembliesengage turbine unit 16 which is in turn press fitted upon bur tube 15.The outer race of bearing assembly 13 also engages stator 12 which inturn bears against cartridge casing 11. At-its lower end, the cartridgecasing engages the outer race of bearing assembly 14. Thus, as thethreaded cap D is tightened within housing B, the entire turbinecartridge assembly is urged downwardly until the outer race of bearingassembly 14 seats against internal shoulder 20 of the housing.

Referring to FIGURES 3 and 4, it will be seen that the bur tube 15 has agenerally cylindrical body portion 21 and an enlarged head portion 22 atits upper end. A bore 23 extends axially through both the body and headportions and is of substantially uniform diameter except at its lowerend where the inner surfaces of the bur tube taper inwardly, asindicated at 24 (FIGURE 4). At its opposite upper end, the bur tube hasits internal surfaces provided with threads 25 for adjustably engagingthe external threads at the upper end 26 of chuck 17.

The chuck 17 is also of generally cylindrical shape and is disposedwithin the bore 23 of bur tube 15. At its lower end, the chucks outersurface tapers inwardly and the wall of the chuck is provided with aplurality of axiallyextending circumferentially spaced slots 27. Thecircumferentially spaced slots define therebetween a plurality of springfingers 28 for gripping and holding a conventional dental bur E withinbore 29.

It is to be noted that bore 29 terminates at a point below the chucksupper end and that along most of its longitudinal extent (and whenspring fingers 28 are in an untensioned state) bore 29 is sufiicientlylarger than the outer diameter of the bur to provide a definiteclearance or spacing therebetween. However, the extreme upper endportion 29a of the bore tapers inwardly to a diameter slightly smallerthan the outside diameter of a bur. Therefore, the frusto-conicalsurfaces 29a at the upper end of bore 29 automatically center the upperend of a bur E within chuck 17 when the bur is fully inserted within thebore.

The upper end portion 26 of chuck 17 is provided with an axial bore 30of non-circular cross section. In the illusjtration given, bore 30 is ofrectangular cross section although it is to be understood that othershapes, such as a hexagonal cross sectional configuration, might beused. If desired, the coaxial bores 29 and 30 may communicate with eachother as shown in FIGURE 4.

Non-circular bore 30 slidably and removably receives the projecting endportion of key shaft 31 provided by collet wrench F. As shown in FIGURES2, 4 and 5, key shaft 31 is of non-circular (square) cross sectionalconfiguration so that when the shaft is received within bore 30, thechuck 17 and the key shaft are locked against independent relativerotation.

Referring to FIGURES 2 and 5, it will be seen that the collet wrench Fis provided with longitudinally aligned upper and lower cylindricalsections 32 and 33, respectively. The lower section is provided with anaxial bore 34 which rotatably receives a stem extension 35 of the uppersection. Key shaft 31 is securely anchored within a socket 36 (FIGURE 4)in the stem extension and, when the parts are assembled as illustratedin FIGURES 2 and 4, the lower end portion of the key shaft projectsdownwardly below the wrenchs lower section 33.

The upper and lower sections of the collet wrench are rotatablyconnected by means of a stop ring 37 (FIG- URES 4 and 5) which istightly fitted upon the key shaft 31 and which is rotatably disposedwithin an enlarged opening 38 in the lower end of section 33. As shownin FIGURE 4, the diameter of the stop ring is larger than the diameterof bore 34; therefore, the collet wrenchs lower section 33 is rotatablysupported upon stem 35 and is restrained against relative axial movementby upper section 32 and by the lower stop ring 37.

To permit insertion of the key shaft 31 into the noncircular bore 30 ofchuck 17, the cap D of the head housing is provided with a centralaccess opening 39 which is in axial alignment with the bore of the chuckand which is not only of substantially greater width than the maximumcross sectional dimensions of the key shaft, but which is preferablyslightly larger in diameter than collet chuck 17 It is believed apparentfrom the foregoing that when the key shaft is inserted through the headhousing and into the bore of chuck 17, rotation of the wrenchs uppersection 32 will cause rotation of the collet chuck. However, unless somelocking means is provided for locking bur tube 15 in place, the rotationof the chuck will be accompanied by simultaneous rotation of the burtube and the turbine.

In the embodiment illustrated in the drawings, such' locking meanscomprises a plurality of locking pins 40 which project downwardly fromthe lower end of the wrenchs lower section 33 and which are arranged inuniformly-spaced circumferential series about key shaft 31.Theoretically, only a single locking pin is needed; however, as apractical matter, to facilitate operation of the wrench and to reducewear and possible injury to the parts, a plurality of such locking pinsis preferred. In the illustration given, three uniformly-spacedpins areused although it is to be understood that a greater or smaller numbermay be provided.

The upper end portions of the pins are tightly fitted within sockets 41extending upwardly from the lower end of the wrenchs lower section. Thelower end portions of the locking pins project downwardly from thewrench a distance sufficient to pass through openings 42 in end cap Dand into sockets 43 in the enlarged head 22 of the bur tube (FIGURE 4).Preferably, the number of openings in cap D corresponds with the numberof locking pins, but the number of sockets 43 in the bur tube is amultiple of the number of pins. In the embodiment illustrated in thedrawings, the bur tube is provided with six sockets 43 (FIGURES 2 and3), the locking pins being adapted to be received in any alternate threesockets provided by the bur tube. Theprovision of an additional numberof bur tube sockets facilitates connection of the wrench when thesockets are not in precise alignment with openings 42 in the end cap. Insuch a case, the key shaft 31, which is substantially longer than thelocking pins, is first inserted into the bore of the collet chuck andthe chuck and bur tube are then rotated (by rotating the upper sectionof the wrench) until three of the bur tube sockets 43 are in directalignment with the pins 40 which have al-v ready been inserted into capopenings 42 and which bear against the upper end of the bur tube. Thelarger number of sockets in the bur tube permits a more rapid couplingof the wrench to the head assembly because it reduces the degree ofrotation of the bur tube which is required before alignment of thesockets and the locking pins is achieved.

Once the locking pins have been received within the sockets of the burtube, the pins anchor the bur tube, the. head housing, and the wrenchslower section against in dependent relative rotation. Thereafter, auser, holding the handpiece in one hand and the upper section 32 of thecollet wrench in the fingers of the other hand, simply rotates thatupper section to thread the collet chuck 17 downwardly or upwardlywithin the bur tube. As the collet chuck is shifted upwardly, springfingers 28 release bur E and the bur may be easily removed from thehandpiece. To facilitate operation of the collet wrench, it is desirableto provide the outer surface of the wrenchs upper section 32 withknurling, as illustrated in FIGURES 2 and 5.

Attachment of a bur is accomplished simply by reversing theabove-described procedure. In this connection, it should be noted thatthe bur, after it has been fully inserted into the bore 2? of the colletchuck and after the chuck has been rotated to force the jaws or fingers28 inwardly into tight frictional engagement with the bur, is held inplace only at the front and rear ends of bore 29. Specifically, the buris engaged only by the tapered rear surfaces 29a and by the front jaws28 of the chuck. Precise axial alignment of the bur is thereby achievedwithout providing a tight fit between the bur and the chuck which mightotherwise interfere with insertion or removal of the bur. Furthermore,the precise orientation of'the bur within the collet chuck eliminatesrapid wear of the bearings which might otherwise occur during high-speedoperation should bur eccentricity exist.

In the unlikely event that a bur should tend to stick within the colletchuck after jaws 28 are released, the bur may be easily pushed from thechuck by inserting a suitable tool (not shown) through opening 39 in endcap and through bore 30 which communicates wit-h bore 29.

Since opening 39 is slightly larger in diameter than chuck 17, there isno danger that unthreading of the chuck to release a bur might cause thechuck to jam against the inner face of end cap D. At the same time,opening 39 provides an effective discharge port for air which leaksthrough bearing assembly 13 to cool and lubricate the ball bearingsthereof.

It will also be observed that the outer surface of bur nut 18 tapersdownwardly and inwardly towards the bur, and that the inner surface 44of the housing adjacent the bur tube nut is similarly tapered, to directa conical stream of air towards the bur. Such a conical stream of airtends to uniformly distribute water discharged from tube 45 onto the burto prevent dry cutting which might otherwise result in the generation ofheat sufficient to damage the nerve of a tooth being drilled.

While in the foregoing I have disclosed an embodiment of the inventionin considerable detail for purposes of illustration, it will beunderstood by those skilled in the art that many of these details may bevaried without departing from the spirit and scope of the invention.

I claim:

1. In combination with a turbine-driven dental handpiece having ahousing, a turbine rotor rotatably mounted within said housing with abore extending therethrough, a collet chuck threadedly received withinsaid bore and having a bore of non-circular cross section extendinginwardly from one end thereof, a socket provided by said turbine rotoradjacent said non-circular bore and extending inwardly at said one end,and opening means in said housing for access to said socket and to saidnon-circular bore; a collet wrench comprising 1) a pair of membersdisposed in axial alignment; (2) means interconnecting said members forindependent relative rotation thereof and locking said members againstrelative axial movement; (3) one of said members having at least onelocking pin projecting from an end thereof opposite from the other ofsaid members and extending along a line substantially parallel to butspaced from the axes of said members; and (4) and the other of saidmembers being provided with an axially-disposed shaft of non-circularcross sectional configuration extending through said one member andprojecting outwardly beyond said one member in spaced parallel relationwith respect to said looking pin; whereby, upon insertion of said shaftinto the non-circular bore of a handpiece and upon the insertion of saidlocking pin into an adjacent rotor socket, said other member of saidwrench may be rotated with respect to said one member and to saidhandpiece to adjust said collet within the rotors threaded bore.

2. The structure of claim 1 in which said members are generallycylindrical in shape.

-3. The structure of claim 1 in which said shaft projects axially fromsaid one member beyond said pin.

4. The structure of claim 1 in which said one mem ber is provided with aplurality of locking pins arranged in a circumferentially-spaced seriesabout said shaft.

5. The structure of claim 1 in which said shaft is of square crosssectional configuration.

6. In combination, a turbine-driven dental handpiece and a collet wrenchtherefor, said handpiece comprising a housing, a turbine rotor rotatablymounted within said housing and having a bore extending therethrough, acollet chuck threadedly received within said bore, said chuck having afirst bore extending inwardly from one end thereof for receiving adental bur and also having a second bore of non-circular cross sectionalconfiguration extending inwardly from the opposite end thereof, and anend opening in said housing in axial alignment with said second bore foraccess thereto, said wrench including a shaft of non-circular crosssectional configuration slidably and removably received within saidsecond bore of said chuck, and locking means provided by said wrench andsaid rotor alongside said shaft for releasably locking said rotoragainst rotation relative to said housing.

7. The structure of claim 6 in which said first bore of said colletchuck is tapered at its inner end for centering a bur inserted therein.

8. The structure of claim 6 in which said locking means includes aplurality of locking pins provided by said wrench and disposed inparallel relation in a circumferentially-spaced series about said shaft,said housing having a plurality of openings immediately adjacent saidfirst-mentioned opening and said rotor having a plurality of socketsadjacent said non-circular bore removably receiving said pins forlocking said rotor against rotation with respect to said housing.

9. The structure of claim 6 in which said wrench is provided withgenerally cylindrical upper and lower sections interconnected in axialalignment for independent relative rotation, means provided by saidupper section extending through said lower section and supporting saidshaft, said shaft projecting through and below said lower section, andsaid pin being mounted upon said lower section and projecting downwardlytherefrom adjacent said shaft.

10. The structure of claim 9 in which said shaft projects downwardlybeyond said pin.

11. The structure of claim 6 in which the first and second bores of saidcollet chuck are in axial communication with each other.

12. A turbine-driven dental handpiece comprising a head housing, aturbine rotor rotatably mounted within said housing and having a boreextending therethrough, said bore being tapered at one end thereof andbeing internally threaded at its opposite end, a collet chuck threadedlymounted within said bore and having a plurality of flexible jawsengagable with the internal surfaces of said rotor at said tapered endof said bore, said chuck having a first bore extending inwardly fromsaid jaws for receiving a dental bur and having a second bore ofnoncircular cross section extending inwardly from its opposite end, saidrotor having at least one socket extending inwardly in an axialdirection from the end thereof adjacent the non-circular bore of saidchuck and spaced laterally from the rotational axis of said rotor, andopening means in an end wall of said housing for access to saidnoncircular bore of said chuck and to said socket of said rotor,whereby, a wrench having a locking pin receivable .in said socket and anindependently rotatable non-circular shaft receivable in the noncircularbore of said chuck may be 7 coupled to said handpiece for adjustment ofsaid collet chuck within said rotor.v

13. The structure of claim 12 in which said rotor is provided with aplurality of sockets extending inwardly in an axial direction from theend thereof adjacent the non-circular bore of said chuck and beingdisposed in a uniformly-spaced circumferential series about saidnoncircular bore.

14. The structure of claim 12 in which said first bore of said colletchuck is tapered at its inner end for centering of a bur insertedtherein.

15. The structure of claim 12 in which said first and second bores ofsaid collet chuck are in axial communication with each other.

16. The structure of claim 12 in which said head housing is providedadjacent the non-circular bore of said chuck with a central openingcoaxial with said chuck and of a diameter slightly larger than that ofsaid chuck.

17. In combination, a turbine-driven dental handpiece and a colletwrench therefor, said handpiece comprising a housing, a turbine rotorrotatably mounted within said housing and having a bore extendingtherethrough, a collet chuck threadedly received within said bore, saidchuck having a first bore extending inwardly from one end thereof forreceiving a dental bur and also having a second bore of non-circularcross sectional configuration extending inwardly from the opposite endthereof, and an end opening in said housing in axial alignment with saidsecond bore for access thereto, said wrench including a shaft ofnon-circular cross sectional configuration slidably and removablyreceived within said second bore of said chuck, and locking meansprovided by-said wrench and said rotor alongside said shaft forreleasably locking said rotor against rotation relative to said housing,said locking means including at least one locking pin provided by saidwrench and disposed in spaced parallel relation with respect to saidshaft, said housing having an end opening immediately adjacent saidfirst-mentioned opening and said rotor having a socket adjacent saidnoncircular bore releasably receiving said pin for locking said rotoragainst rotation with respect to said housing.

References Cited UNITED STATES PATENTS 3,120,706 2/1964- Turchi et a1.32-27 FOREIGN PATENTS 1,274,907 9/1961 France.

RICHARD A. GAUDET, Primary Examiner. ROBERT E. MORGAN, Examiner.

12. A TURBINE-DRIVEN DENTAL HANDPIECE COMPRISING A HEAD HOUSING, ATURBINE ROTOR ROTATABLY MOUNTED WITHIN SAID HOUSING AND HAVING A BOREEXTENDING THERETHROUGH, SAID BORE BEING TAPERED AT ONE END THEREOF ANDBEING INTERNALLY THREADED AT ITS OPPOSITE END, A COLLECT CHUCKTHREADEDLY MOUNTED WITHIN SAID BORE AND HAVING A PLURALITY OF FLEXIBLEJAWS ENGAGEABLE WITH THE INTERNAL SURFACES OF SAID ROTOR AT SAID TAPEREDEND OF SAID BORE, SAID CHUCK HAVING A FIRST BORE EXTENDING INWARDLY FROMSAID JAWS FOR RECEIVING A DENTAL BUR AND HAVING A SECOND BORE OFNONCIRCULAR CROSS SECTION EXTENDING INWARDLY FROM ITS OPPOSITE END, SAIDROTOR HAVING AT LEAST ONE SOCKET EXTENDING INWARDLY IN AN AXIALDIRECTION FROM THE END THEREOF ADJACENT THE NON-CIRCULAR BORE OF SAIDCHUCK AND SPACED LATERALLY FROM THE ROTATIONAL AXIS OF SAID ROTOR, ANDOPENING MEANS IN AN END WALL OF SAID HOUSING FOR ACCESS TO SAIDNONCIRCULAR BORE OF SAID CHUCK AND TO SAID SOCKET OF SAID ROTOR,WHEREBY, A WRENCH HAVING A LOCKING PIN RECEIVABLE IN SAID SOCKET AND ANINDEPENDENTLY ROTATABLE NON-CIRCULAR SHAFT RECEIVABLE IN THENON-CIRCULAR BORE OF SAID CHUCK MAY BE COUPLED TO SAID HANDPIECE FORADJUSTMENT OF SAID COLLET CHUCK WITHIN SAID ROTOR.